Since you're asking what to expect...
Mix the prep up with chilled water, add some fruit juice (not red) or a squirt of the sugar free drinks flavourings (still not a red one). Drink it through a straw to the back of your throat. I used orange juice. (Which in case you're worrying, I've had to drink this vile stuff in the hospital as well and they provided orange juice that time. So it is fine to add it.)
You're supposed to do a litre of prep every 60-90 minutes. I mixed it, then poured it into a 250ml and drank it as fast as I could in 4 goes. For me, trying to drink it slowly across the hour means the smell and taste make you start to gag. You'll probably need to drink the fourth cup more slowly as the smell might be reaching you. (I tried to mix the next one up after I'd finished drinking the obvious one, or an hour in advance for the first dose, then put it in the fridge until I was ready).
You may not need to drink all 4 litres. If what you're passing is clear after the 3rd litre, the 4th isn't necessary. It should say that in the instructions though.
If you find yourself gagging a bit, stop for a few minutes, take a few sips of water, then resume a bit more slowly. You don't want to end up bringing any of it up again (as I did - probably wouldn't have needed to drink the 4th litre if I hadn't!). It is not any better coming up than going down. I don't recommend it.
If you (more or less) neck it then you can spend the rest of the hour following the second instruction to drink water (I think it was a litre of water every hour or two you're doing the prep). I had a cup of fruit juice mixed with water, plus fruit tea (no milk obviously) and sipped the two over the hour til the next dose while I sat with my laptop or whatever. That way by the time you're taking the next dose the taste/smell has faded. The moviprep doesn't count as water.
You might need to psych yourself up a bit by the last litre, but just focus on counting down and it nearly being over.
Afterwards you go to a recovery room where you lie on a trolley until you feel awake enough to sit up. Your obs will be checked. If you're well enough you can get dressed and then go to seated recovery. Once you've sat there for a while and managed to have a drink and a biscuit, they'll let you go home with your escort if you are fit and well.
How quickly you're discharged depends on how well you recover from the sedation, but it is effectively an anaesthetic recovery routine. So no driving, operating machinery (including ovens and kettles), signing legal documents, etc for 24 hours.
For me, I had to be admitted overnight as I was really sick from the sedation. But everybody else in recovery with me was fine and went home fairly rapidly!
I still felt woozy for another couple of days, and had stomach pains for about three days.
You might want to have some jellies in the fridge for afterwards in case you can't face normal food straight away. But other people in recovery when I was there were fantasising about what they were having for dinner. Listen to your body.
I was worried I'd be really hungry, but once you start the prep you feel too full from the prep itself and all the liquids you have to drink on top to prevent dehydration, so I didn't notice any hunger. I didn't actually eat for nearly 2 days, and was fine.
Remember to start drinking again afterwards as you might end up more woozy otherwise.
Most of it sounds worse because it's unknown. If you have a plan and talk yourself through it it's fine. I set myself up with a selection of distractions for while I was doing the prep depending on how rough I felt, and packed a bag for hospital with bits and pieces to occupy me and snacks for afterwards. I did take overnight stuff in case I had to be kept in, luckily.
People make the prep sound terrible, but once it started working it was predictable. I rested in the room next to the bathroom, I didn't need to actually stay in there. Drinking the prep was much worse than its effects to be honest!